1) the most confounding point is why austria attacked serbia, knowing it was going to spark a war against russia. you can say something about historical control or whatever, but none of the arguments are really good. the only thing that makes any sense to me - besides outright idiocy - is that they were trying to dismantle prussia under the hope that they'd gain control in the end. that is, it might have been a sneaky tactic to unite the german heartland under hapsburg rather than hohenzollern control. that makes it an indirect result of the austro-prussian war of 1866, and ultimately an inter-german conflict.
2) russia had long been looking for an excuse to "unite the slavs". they were aiming to dismantle austria and absorb most of it. this is well understood.
3) the ottomans had their own interests in eastern europe and saw russian expansion as a security threat.
4) the germans knew that the belgians were not truly neutral. that's the unstated point, the necessary revision. if they left belgium sitting on the coast, it would have opened up staging grounds and spy networks. if they were going to invade france (and they had to to deal with the two front problem), they had no choice but to attack belgium.
5) i agree that the french saw the germans as weak and intended to dismantle them, with russian help. but, they expected the russians to do most of the work.
6) the british involvement had less to do with europe and more to do with africa. "belgian neutrality" meant "not taking over belgian colonies in africa". the british were both interested in reducing german influence in africa and, frankly, in not letting the germans get the spoils of belgian absorption. they may have agreed with the principle of neutrality so long as belgium was under de facto british alliance, but as soon as the germans invaded the congo became up for grabs.
7) the americans intervened largely to prevent a socialist revolution in germany and france, after what was happening in russia became clear.
the thing that screwed everything up for the western powers (and austria) and created the stalemate was russia's greater interest in the south than the north. had russia marched straight to berlin as they were supposed to, the prussians would have been dismantled and probably partitioned, and the british would have taken over most of their colonies in africa. oddly, the british and french may have ended up aligning with the ottomans in a drawn out russian-ottoman conflict that may have seen deep russian penetration into the middle east.
this is a dramatically different outcome and potential world order, and was likely made in a snap decision by the russian generals.